The random alignment of maternal and paternal homologous chromosomes during metaphase I is one of the ways genetic variability among gametes comes about. For example, it is possible for an organism with 4 pairs of homologous chromosomes to produce gametes with up to 16 different combinations of maternal and paternal chromosomes. In the case of humans with 23 pairs of chromosomes, there are over 8 million possible combinations. How many possible combinations of maternal and paternal chromosomes are possible in the gametes of an organism with a diploid number of 16 chromosomes?

256 possible combinations.

Explanation:

Homologous chromosomes consist of one maternal chromosome and one paternal chromosome that pair up during meiosis. They have the same genes in the same loci, but not alleles.

During metaphase I they line up in a random order, this means there are different combinations of maternal and paternal chromosomes for each gamete.

There are 2 alternatives for each pair of homologous chromosomes. We calculate then the number of gametes with different chromosomic combinations as 2^n, being n the number of homologous pairs or haploid number of an organism.

For an organism with 4 pairs of homologous chromosomes: 2^4 = 16

For humans with 23 pairs of chromosomes: 2^23 = 8,388,608‬

For an organism with a diploid number of 16 chromosomes, we have 8 pairs of homologous chromosomes (haploid number, one set of chromosomes):

2^ 8 = 256 possible combinations of maternal and paternal chromosomes.